• Sauté the aromatics. Heat the olive oil in a large soup pot over medium heat. Add the onion, garlic, and leek and cook until softened, about 4 minutes.
• Add the chicken and broth. Add the celery, chicken, white wine, tarragon, and chicken broth. Bring to a boil, then reduce the heat and simmer, stirring occasionally and turning the chicken once or twice, until the chicken is cooked through and tender, about 30 minutes.
• Blend the soup. Remove the chicken from the pot and set aside. Use an immersion blender to blend the soup until smooth and creamy.
• Shred the chicken. Discard the bones and skin and shred or chop the chicken.
• Finish the soup. Stir in the heavy cream and lemon juice, then return the chicken to the pot. If using fresh tarragon, stir it in now. Heat gently until warmed through.
• Season and serve. Add salt and freshly ground black pepper to taste and serve warm.

Instant Pot Instructions

• Sauté the vegetables. Set the Instant Pot to Sauté. Heat the olive oil, then add the onion, garlic, leek, and celery. Cook for 4–5 minutes, until softened.
• Deglaze the pot. Add the white wine and scrape up any browned bits from the bottom.
• Pressure cook. Add the chicken, broth, and dried tarragon. Lock the lid, set the valve to Sealing, and cook on High Pressure for 15 minutes. Allow a 10-minute natural release, then quick-release any remaining pressure.
• Blend the soup. Remove the chicken from the Instant Pot and set aside. Use an immersion blender to blend the soup until smooth and creamy.
• Shred the chicken. Discard the bones and skin and shred or chop the chicken.
• Finish the soup. Stir the heavy cream and lemon juice into the soup, then return the chicken to the Instant Pot. If using fresh tarragon, stir it in now. Season with salt and pepper to taste.

Slow Cooker Instructions

• Sauté the aromatics. Heat the olive oil in a skillet over medium heat. Add the onion, garlic, and leek and cook for 3–4 minutes, until softened. Transfer to the slow cooker.
• Add the remaining ingredients. Add the celery, chicken, white wine, chicken broth, and dried tarragon. Season lightly with salt and pepper.
• Cook. Cover and cook on Low for 7–8 hours or High for 4–5 hours, until the chicken is tender and cooked through.
• Blend the soup. Remove the chicken from the slow cooker and set aside. Use an immersion blender to blend the soup until smooth and creamy.
• Shred the chicken. Discard the bones and skin and shred or chop the chicken.
• Finish the soup. Stir in the heavy cream and lemon juice, then return the chicken to the slow cooker. If using fresh tarragon, stir it in now. Cover and cook for about 10 minutes longer, until everything is warmed through.
• Season and serve. Taste and adjust the salt and pepper before serving.